Psilocybin was first synthesised in 1958 by Sandoz, see GB912714 and U.S. Pat. No. 3,075,992, and was widely available as a research chemical until the mid-1960's.
A plant based psychedelic it has been used as an aide to psychotherapy for the treatment of mood disorders and alcoholic disorders and recently 3 clinical trials have reported its use for depressive symptoms.
Griffiths et al 2016; J Psychopharmacol 30 (12):1181-1197;
Ross et al 2016; J Psychopharmacol 30 (12):1165-1180; and
Carhart-Harris et al 2016, Lancet Psychiatry 3(7): 619-627.
Methods of manufacture of psilocybin are limited and include:
J Nat Prod 2003, 66, pages 885-887;
Hely Chim Acta 1959, 42, 2073-2103;
Experientia 1958, 15, 397-399; and
Synthesis 1999, 935-938.
Based on this literature Applicant believed that the process disclosed in J Nat Prod 2003, 66, pages 885-887 (hereafter JNP) was the most suitable method for development into a commercial scaled process.
The process disclosed therein produced quantities in the order of 10 g and comprised 6 steps numbered (i) to (vi).
By analogy with the Applicants process, steps ii and iii are hereafter discussed as a single step, (Step 2) and the JNP process is reproduced as FIG. 1 herein.
Step 1 (i) comprised reacting 4-hydroxyindole (“3”) with acetic anhydride (Ac2O) in pyridine and anhydrous dichloromethane (CH2Cl2) at 0° C. Water was added, the mixture evaporated, and the resulting concentrate was dissolved in ethyl acetate, washed with water, and saturated sodium chloride, and the organic phase dried over sodium sulphate and evaporated to obtain 4-acetylindole (“4”), which was collected by filtration and washed with water and ethyl acetate.
Step 2 (ii and iii), a two-step acylation (ii)—amidation step (iii), comprised forming 3-Dimethylaminooxalyl-4-acetylindole (“6”) by: (ii) reacting 4-acetylindole (“4”) with oxalyl chloride ((COCl)2) in anhydrous diethylether, stirring, adding n-hexane and holding at −20° C. to produce an intermediate 3-(2-chloro-2-oxoacetyl)-1H-indol-4-yl acetate (“5”) which was separated by filtration. The intermediate was dissolved in anhydrous tetrahydrofuran (THF) and reacted with dimethylamine ((CH3)2NH) in tetrahydrofuran and pyridine. Anhydrous ether was added because of solidification, and the reaction product separated by filtration and washed with n hexane, ethyl acetate, and water to obtain 3-Dimethylaminooxalyl-4-acetylindole (“6”).
Step 3 (iv) comprised the formation of psilocin (“1”) by reacting the 3-Dimethylaminooxalyl-4-acetylindole (“6”) with lithium aluminium hydride (LiAlH4) in anhydrous THF under an argon atmosphere. After refluxing and cooling, anhydrous sodium sulphate was added, followed by a solution of sodium sulphate, and further anhydrous sodium sulphate. The reaction mixture was diluted with ethyl acetate, quickly concentrated in vacuo, and the resulting psilocin crystals briefly washed with methanol.
Step 4 (v) comprised the formation of benzyl [2-(4-oxyindol-3-yl) ethyl] dimethylammonio-4-O-benzyl phosphate (“8”) by reacting psilocin, dissolved in anhydrous THF, with n-butyl lithium (n-BuLi) in n-hexane at −78° C. and tetrabenzylpyrophosphate [(BnO)2PO]2O, and the reaction allowed to warm to 0° C., and the production of intermediate dibenzyl 3-[2-(dimethylamino)ethyl]-1H-indol-4-yl phosphate (“7”) monitored. On checking for its presence, aminopropyl silica gel was added, the mixture diluted with ethyl acetate and filtered through a Celite pad by suction, the filtrate concentrated in vacuo, re-dissolved in CH2Cl2, and the precipitate collected by filtration.
Step 5 (vi) comprised the formation of psilocybin (“2”) by reaction of (“8”), in methanol (MeOH), with hydrogen (H2) using a palladium-activated carbon catalyst (Pd/C). Water was added, because of product deposition, and (“8”), its mono de-benzylated derivative were monitored along with the appearance of psilocybin, the reaction solution was filtered through a Celite pad. The product was collected by filtration and washed with ethanol to provide a white needle crystalline form with a melting point 190° C.-198° C.
In contrast to most processes, such as JNP, which use non-aqueous solvents, such as methanol or ethanol, Experientia 1958, 15, 397-399 used a single re-crystalisation from water to obtain psilocybin from a mushroom extraction. The teaching was to use boiling water to dissolve the starting material, obtained at small scale by chromatography, and the resulting high vacuum dried material was stated to melt indistinctly between 185 and 195° C., and showed a weight loss of 25.4%, suggesting it clearly differs in purity and form to that obtained by Applicant.
During the development of a synthesis to produce Psilocybin the applicant conducted a number of hydrogenation reactions on a 5 g scale which resulted in different crystalline forms of Psilocybin being obtained. The initial hydrogenation reaction yielded Hydrate A (JCCA2157E) which exhibited a XRPD diffractogram as shown in FIG. 7d and DSC and TGA thermograms as shown in FIG. 8d. The DSC exhibits an endotherm at ˜97° C. which is coincidental with a weight reduction in the TGA indicative of dehydration, and an endothermic event with an onset temperature of ˜216° C. which was presumed to be the melt. Another hydrogenation reaction yielded an ethanol solvate (JCCA2158D) which when analysed by XRPD (FIG. 7e), DSC (FIG. 8e), TGA (FIG. 8e) and by 1H NMR indicated 11% entrapped ethanol. The DSC thermogram shows an endotherm having an onset of ˜154° C. that appeared to be a melt concurrent with the ˜13% weight loss in the TGA. In another experiment performed during development, the applicant performed a crystallisation of psilocybin; rather than remain in solution in hot water allowing for a polish filtration step, precipitation occurred at high temperature (>90° C.). The solids formed did not re-dissolve upon further heating or addition of extra water. Upon cooling and isolation of the solid (CB646E) XRPD was performed. The XRPD diffractogram (FIG. 7f) suggested a mixed phase of Polymorph A′ (JCCA2160-F-D4) and Polymorph B (JCCA2160-F-TM2-c5). These findings highlight the importance of developing a process which can consistently produce the desired crystalline form so the Applicants set about experiments to determine what these forms were in order they could produce a chemically pure psilocybin, in a controlled form suitable for use in medicine.
For clinical trials any New Active Substance (NAS) should be capable of large scale production (typically 100 g plus, more typically greater than 250 g, more preferably still greater than 500 g, to Kg plus batches), depending on the amount of active to be dosed to a human subject. It should also be chemically pure, well defined, and stable on storage.
Furthermore, any method of manufacture must be readily reproducible, and provide batch to batch consistency.
It is a first object of this invention to provide psilocybin, of consistent polymorphic form, for administration to human subjects.
It is another object of this invention to provide chemically pure psilocybin, of consistent polymorphic form, for administration to human subjects.
It is yet a further object to provide chemically pure psilocybin, in large scale batch quantities since for commercial use, the pure psilocybin must be produced at scale.
It is yet a further object of the invention to provide a method of crystallising psilocybin in a desired polymorphic form.
It is yet a further object of the present invention to provide a scalable method for manufacturing psilocybin, from psilocin or 4 hydroxy-indole.
In developing suitable methodology Applicant experienced numerous problems and difficulties which they had to be overcome, and it is a separate, independent, object to overcome those problems identified at each step, and use the inventions either alone or in combination.
It is yet a further object of the invention to formulate the psilocybin of the invention in a form suitable for administration to human subjects and use it in medicine, particularly in the treatment of central nervous system disorders (CNS), and more particularly, but not exclusively, in the treatment of depression, particularly, drug resistant depression either alone or in combination with a digital health product or digital solution.